Energy storage is a crucial component of a large number and variety of electronic devices, particularly for mobile devices and electric or hybrid vehicles. Energy storage devices have been based on a wide variety of physical effects. For example, electric fields can be employed to store energy in capacitors, and chemical reactions (involving ion motion) can be employed to store energy in batteries. However, energy storage in a capacitor can be limited by the device geometry (e.g., 2-D capacitor plates having limited area), and batteries can have a slow response time due to the ion motion inherent in electrochemical reactions.
Battery powered devices such as hybrid or electric vehicles are often limited in performance by the low energy stored per weight in batteries. Batteries have low storage density due to the low voltage produced by electrochemical reactions and the large size and weight of the ions stored in the batteries. Slow ion transport in batteries also causes slow charge and discharge performance. Furthermore, the reliance of existing batteries on ionic transport causes high degradation rates of the batteries.
Accordingly, it would be an advance in the art to provide energy storage having higher energy density than a capacitor, faster charge/discharge than a battery and/or much longer lifetime than a battery.